Answers

2015-08-23T14:56:59+05:30
For example
Tyres are a period of time get loose their grip and become smooth  due to friction
Engine gets heated up due to friction

We can reduce friction by adding lubricants or oils
For example we use oil in cycle chains to reduce friction
                     we add lubricants in machines to reduce friction
                     we add oil in engines to reduce hat produced by friction
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2015-08-23T17:11:02+05:30
It depends on the nature of surfaces of two bodies in contact.
it is difficult to move objects due to friction
by polishing 
by using of ball bearings by use of lubricats

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